The adequate treatment of pain continues to be a mjor challenge for clinicians. The relative inadequacy of pain management has been well documented for ambulatory and hospitalized pediatric patients and persists despite the large number of effective opioid and non-opiate analgesics available for clinical use. Oxycodone is a semi-synthetic, pure opioid agonist with properties similar to morphine. It has been used for the treatment of moderate to moderately severe pain in adult patients. The objective of this study is to compare the extent of oxycodone absorption and related pharmacokinetic paramenters after the administration to children of a single dose of immediate-release oxycodone and controlled-release oxycodone. Ten subjects have been enrolled to date.